New England Distribution

Non-native: introduced
(intentionally or
unintentionally); has become naturalized.

County documented: documented
to exist in the county by
evidence (herbarium specimen, photograph). Also covers
those considered historical (not seen in 20 years).

State documented: never been
documented from the
county, but known from the state. May be present. Or,
may be restricted to a small area or a habitat (alpine,
marsh, etc.), so unlikely found in some
counties.

Note: when native and non-native
populations both exist in a county, only native status
is shown on the map.

North America Distribution

Facts About

Stiff sunflower is a complicated, variable species with two subspecies as well as a rare stable hybrid (frequently cultivated), all of which are found in most New England states. This may pose more than the usual challenges to identification.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

Characteristics

Habitat

terrestrial

New England state

Connecticut

Maine

Massachusetts

New Hampshire

Rhode Island

Leaf type

leaves are simple (i.e., lobed or unlobed but not separated into leaflets)

Leaf arrangement

alternate: there is one leaf per node along the stem

opposite: there are two leaves per node along the stem

whorled: there are three or more leaves per node along the stem

Leaf blade edges

the edge of the leaf blade has no teeth or lobes

the edge of the leaf blade has teeth

Flower type in flower heads

the flower head has tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery

Ray flower color

yellow

Tuft or plume on fruit

there is no plume, or the plume is made up of scales, awns, a crown, or a rim

ssp.pauciflorus

ssp.subrhomboideus

Native to North America?

Sometimes Confused With

reproductive stems with mostly 3–5 nodes bearing highly reduced leaves or rarely the lower 2–4 nodes with well-formed blades, often the upper 50% of the stem lacking leaves, and plants with a basal rosette of leaves (vs. H. pauciflorus, with reproductive stems with mostly 6–15 or more leaf-bearing nodes, the blades gradually, if at all, decreasing in size upward, only the upper 25% or less of the stem lacking leaves, and plants often without a basal rosette of leaves).

Synonyms

Helianthuslaetiflorus Pers. var. rigidus (Cass.) Fern.

Helianthusrigidus (Cass.) Desf.

Family

Genus

Notes on Subspecies and Varieties in New England

Subspeciespauciflorus is known from CT, MA, ME, NH, RI. Subspecies subrhomboideus is known from CT, MA, ME, NH. Clevengerand Heiser (1963) gave detailed accounts of crossing studies that suggested Helianthus ×‌laetiflorus is best treated as a hybrid (see below) and that ssp. pauciflorus may have arisose through through hybridization between H. pauciflorus ssp. subrhomboideus and H. tuberosus with later character segregation such that the stabilized entity closely resembles the former parent. Introgression with the latter species would explain the taller stems, longer leaves that are often alternate above, and longer petioles.

Subspecies
pauciflorus is known from
CT, MA, ME,
NH,
RI. Subspecies
subrhomboideus is known from
CT, MA, ME,
NH. Clevenger and Heiser (1963) gave detailed accounts of crossing studies that suggested
Helianthus
×‌laetiflorus is best treated as a hybrid (see below) and that ssp.
pauciflorus may have arisose through through hybridization between
H. pauciflorus ssp.
subrhomboideus and
H. tuberosus with later character segregation such that the stabilized entity closely resembles the former parent. Introgression with the latter species would explain the taller stems, longer leaves that are often alternate above, and longer petioles.

12×15.
Helianthus pauciflorus
×
Helianthus tuberosus
→Helianthus×‌laetiflorus
Pers. is a rare hybrid sunflower that frequently occurs in the absence of its parents. It is known from
CT, MA, ME,
NH,
RI,
VT. It is similar to
H. pauciflorus in regard to involucre characteristics and often disk corolla color (though the corollas can also be yellow), but the involucral bracts are oblong-lanceolate with an acuminate apex, are sometimes sparsely short-pubescent abaxially, and 7–12 mm long (vs. elliptic to oblong-ovate, acute to obtuse, ± glabrous abaxially, and 6–10 mm long; lanceolate with an acuminae apex, hispid abaxially, and 8.5–15 mm long in
H. tuberosus). It also occasionally shows the branching tubers of
H. tuberosus.